When a user inputs a print command to an external device connected to an image forming device, the external device generates output data and transmits the output data to the image forming device. The image forming device receives the output data, and creates an output image to perform printing, based on the output data. In this case, printing may be performed by completing creation of at least one page of the output image.
When a controller of the image forming device transmits a driving signal to an engine or an image forming job unit of the image forming device, the engine is driven to warm up the image forming device, and the image forming device performs printing after the warming up is completed. In this case, in order to prevent a delay in printing due to a warm-up time of the image forming device, a method of transmitting the driving signal to the engine of the image forming device as soon as a user inputs the print command is used. This method is referred to as an early warm-up.